You don't have to specify exactly which source each statement comes from (although it is preferred where possible). Just listing the references at the end of the article would be acceptable.
Wouldn't work. I know that stuff is in books be remembering which childrens book on canals (most stuff above that level will assume you know it and start talking about specific cases) I originaly ran across it. Yes the section could be refed but you would better spending your time sorting out the lack of a mention of the indian canals and the failure to mention the ship canal building boom.
I don't understand. I'm talking about the details of where to mention the sources, and you're responding with what appears to be (you seem to have missed the end of the second sentence off in addition to some typos, so I'm guessing at what you're trying to say) an argument about not needing to cite common knowledge, which is another debate entirely. When making a counter argument, please make sure it is actually related to the original argument.